Chest
Clinical Investigations in Critical CareApplied PEEP During Pressure Support Reduces the Inspiratory Threshold Load of Intrinsic PEEP
Section snippets
MATERIALS AND METHODS
Patients requiring mechanical ventilatory support for OAD over a 12-month period in our medical ICU were eligible for study. To be selected, patients had to be the following: (1) in clinically stable condition; (2) judged not ready for extubation; and (3) on a stand-alone PS ventilator weaning protocol. In our institution, the PS ventilator weaning protocol is instituted when patients recover their spontaneous ventilatory drive and the underlying acute disease has stabilized or is reversing.
RESULTS
Thirteen patients were studied with a mean (±SD) age of 58±3.8 years. Seven patients were men. Two patients had a diagnosis of asthma and 11 had a diagnosis of COPD. The baseline physiologic data are given in Table 1. As can be seen, these patients had mild baseline hypercarbia and high minute ventilation needs (mean delivered minute ventilation of 13.9 L/min). All patients had a measurable APes (PEEPi) with the mean being 9.4 cm H2O. Seven of the 13 patients (54%) had values greater than 10 cm
DISCUSSION
Alveolar pressure can remain above ventilator circuit pressure at end expiration in mechanically ventilated patients with obstructive airway disease through several mechanisms. These include narrowed collapsing airways (flow limiting segments) that can both retard or prevent expiratory flow,1, 2, 3, 4, 5 an inadequate expiratory time for the delivered tidal breath,3, 15, 20 and expiratory muscles remaining active up to the point of breath initiation.7, 21
Pes measurements are often taken as a
ACKNOWLEDGMENT
The authors are indebted to Janet Johns for her secretarial help.
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Cited by (82)
Controlled cycles in spontaneous-timed noninvasive ventilation: Incidence and associated factors
2022, Respiratory MedicineCitation Excerpt :However, it is also possible that those with a greater PS could generate a higher level of hyperinflation, and have air trapping and difficulty activating the ventilator, entering controlled cycles more frequently [25]. Likewise, lower PEEP levels may not have counterbalanced autoPEEP, generating ineffective efforts that triggered a control cycle [26]. The study data show that captured patients do not have less effective ventilation.
Patient-Ventilator Synchrony
2022, Clinics in Chest MedicineExpiratory Flow Limitation During Mechanical Ventilation
2018, ChestCitation Excerpt :Cardiac output may decrease and eventually impairs oxygen delivery.35 In addition, a high PEEPi can remarkably increase the work of breathing by creating an inspiratory threshold load.36,37 Dynamic hyperinflation also flattens the diaphragm, worsening its contractive function and facilitating diaphragm injury.19,38
Managing Respiratory Failure in Obstructive Lung Disease
2016, Clinics in Chest MedicineCitation Excerpt :PEEPe is generally set at no more than 80% of PEEPi levels, because further increases generally worsen measures of dynamic hyperinflation.53 An esophageal balloon can be used to measure PEEPi and guide titration of PEEPe.54 Alternatively, PEEPe can be increased gradually by closely observing the patient–ventilator interaction, VT, and inspiratory pressures.55
Patient-Ventilator Interactions
2016, Clinics in Chest MedicineCitation Excerpt :The triggering load from intrinsic PEEP can also be reduced by the careful use of applied circuit PEEP. This will narrow the gradient between circuit and intrinsic PEEP and lessen the imposed load.22,24 This can be guided by the use of an esophageal balloon or careful bedside application of PEEP by the clinician.
Partially supported by a research grant from Bicore Inc, Irvine, Calif (now Allied Health Care Products, Riverside, Calif).